I have stock 454's with holly carbs and thunderbolt ignition. The port motor sounds as if its not firing on all cylinders but runs fine above idol. However when you put it in gear the RPMs drop quick so you have to give it a little throttle to kept it going. It runs great after that with no problems. I have changed the plugs, wires, cap, coil, and rotor and nothing has worked!!!!

Any ideas???

Is the carb flooding?

I dont believe so but I can check. What is the best way to do so?? Is that a problem that can just start? It has been fine until I did about a 45 mile harbor hop and the problem started the next day

You might have a piece of debris stuck in one of your idle circuit air or fuel bleeds.

Drain the bowl of the carb into a cup and check for water in the fuel. When the boat sits the water lays on the bottom of the bowl if there are any and makes it hard to start and hard to keep idleing in gear.

What is the best way to clean that out?

Check the front float. Make sure bowl has gas to the sight screw.

Pull off the bowls and metering blocks. Spray carb cleaner through all the holes in the metering blocks and then compressed air.

It could be that, but I would also verify that the timing has not moved first.

Also, does it seem like its running rich at idle???? It could be blown powervalve.

I doubt its water in the fuel. It would run like crap all the time, not just at idle.

you might try tweaking your idle mixture setting before digging in too deep. try turning them in or out a bit

[QUOyou might try tweaking your idle mixture setting before digging in too deep. try turning them in or out a bit TE][/QUOTE]yes try that first